Hyperglycaemia-induced impairment of endothelium-dependent vasorelaxation in rat mesenteric arteries is mediated by intracellular methylglyoxal levels in a pathway dependent on oxidative stress

Abstract

Aims/hypothesisImpaired nitric oxide (NO)-dependent vasorelaxation plays a key role in the development of diabetic vascular complications. We investigated the effect of hyperglycaemia on impaired vasoreactivity and a putative role therein of the AGE precursor methylglyoxal.MethodsThe effects of high glucose and methylglyoxal on NO-dependent vasorelaxation in isolated rat mesenteric arteries from wild-type and transgenic glyoxalase (GLO)-I (also known as GLO1) rats, i.e. the enzyme detoxifying methylglyoxal, were recorded in a wire myograph. AGE formation of the major methylglyoxal-adduct 5-hydro-5-methylimidazolone (MG-H1) was detected with an antibody against MG-H1 and quantified with ultra-performance liquid chromatography (tandem) mass spectrometry. Reactive oxygen species formation was measured with a 5-(and-6)-chloromethyl-2′7′-dichlorodihydrofluorescein diacetate acetyl ester probe and by immunohistochemistry with an antibody against nitrotyrosine.ResultsHigh glucose and methylglyoxal exposure of mesenteric arteries significantly reduced the efficacy of NO-dependent vasorelaxation (p < 0.05). This impairment was not observed in mesenteric arteries of GLO-I transgenic rats indicating a specific intracellular methylglyoxal effect. The diabetes-induced impaired potency (pD2) in mesenteric arteries of wild-type rats was significantly improved by GLO-I overexpression (p < 0.05). Methylglyoxal-modified albumin did not affect NO-dependent vasorelaxation, while under the same conditions the receptor for AGE ligand S100b did (p < 0.05). Methylglyoxal treatment of arteries increased intracellular staining of MG-H1 in endothelial cells and adventitia by fivefold accompanied by an eightfold increase in the oxidative stress marker nitrotyrosine. Antioxidant pre-incubation prevented methylglyoxal-induced impairment of vasoreactivity.Conclusions/interpretationThese data show that hyperglycaemia-induced impairment of endothelium-dependent vasorelaxation is mediated by increased intracellular methylglyoxal levels in a pathway dependent on oxidative stress.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-010-1677-0) contains supplementary material, which is available to authorised users.

Glyoxalase-1 overexpression reduces endothelial dysfunction and attenuates early renal impairment in a rat model of diabetes

“…We previously addressed the reaction of the mesenteric endothelium to acetylcholine after short-time incubations with MGO or high glucose and in diabetic rats 12 weeks after STZ injection [14]. In the current study we confirmed these data in mesenteric arteries after 24 weeks of diabetes and extended our observations by specifically addressing which pathways are involved in the diabetes-induced impairment of acetylcholine-dependent relaxation.…”

“…Measurement of vascular function, morphology and gene expression Vascular reactivity was measured as described earlier [14]. For further details see electronic supplementary materials [ESM] Methods.…”

“…Furthermore, we recently demonstrated in an ex vivo model that high glucose levels and short-term diabetes-induced impairment of endothelium-dependent vasorelaxation in rat mesenteric arteries are mediated by intracellular MGO levels [14]. In addition, Glo1 overexpression protects against diabetes-induced retinal neuroglial and vasodegenerative pathology [15].…”

Protection against methylglyoxal-derived AGEs by regulation of glyoxalase 1 prevents retinal neuroglial and vasodegenerative pathology

“…GLO1-overexpressing rats were crossed with wild-type (WT) Wistar rats to obtain enough GLO1 progeny for the experiment. The rats were obtained from the Nippon Seibutsu Zairyo Center (Saitama, Japan) and studies using these animals have been recently published [19,20]. All animal studies were carried out in accordance with the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health.…”

“…This was accompanied by protection against high glucose-mediated dysfunction [17,18]. Overexpression of GLO1 in diabetic rats has been shown to be protective against AGE formation and oxidative stress in muscle [19], and also prevent abnormalities in endothelium-dependent vasorelaxation [20]. Likewise, regulation of GLO1 activity in cells can prevent diabetes-related cell dysfunction [21,22].…”